Scala LinearRegressionWithSGD类代码示例

//设置package包名称以及导入依赖的类
package optimizers

import breeze.linalg.{DenseVector, Vector}
import org.apache.spark.mllib.classification.{LogisticRegressionWithSGD, SVMWithSGD}
import org.apache.spark.mllib.optimization.{L1Updater, SimpleUpdater, SquaredL2Updater, Updater}
import org.apache.spark.mllib.regression.{LabeledPoint, LinearRegressionWithSGD}
import org.apache.spark.rdd.RDD
import utils.Functions._

import scala.tools.cmd.gen.AnyVals.D




class MllibSGD(val data: RDD[LabeledPoint],
               loss: LossFunction,
               regularizer: Regularizer,
               params: SGDParameters,
               ctype: String
              ) extends Optimizer(loss, regularizer) {
  val opt = ctype match {
    case "SVM" => new SVMWithSGD()
    case "LR" => new LogisticRegressionWithSGD()
    case "Regression" => new LinearRegressionWithSGD()
  }

  val reg: Updater = (regularizer: Regularizer) match {
    case _: L1Regularizer => new L1Updater
    case _: L2Regularizer => new SquaredL2Updater
    case _: Unregularized => new SimpleUpdater
  }

  ctype match {
    case "SVM" => opt.asInstanceOf[SVMWithSGD].optimizer.
      setNumIterations(params.iterations).
      setMiniBatchFraction(params.miniBatchFraction).
      setStepSize(params.stepSize).
      setRegParam(regularizer.lambda).
      setUpdater(reg)
    case "LR" => opt.asInstanceOf[LogisticRegressionWithSGD].optimizer.
      setNumIterations(params.iterations).
      setMiniBatchFraction(params.miniBatchFraction).
      setStepSize(params.stepSize).
      setRegParam(regularizer.lambda).
      setUpdater(reg)
    case "Regression" => opt.asInstanceOf[LinearRegressionWithSGD].optimizer.
      setNumIterations(params.iterations).
      setMiniBatchFraction(params.miniBatchFraction).
      setStepSize(params.stepSize).
      setRegParam(regularizer.lambda).
      setUpdater(reg)
  }

  override def optimize(): Vector[Double] = {
    val model = opt.run(data)
    val w = model.weights.toArray
    DenseVector(w)
  }
} 

//设置package包名称以及导入依赖的类
package com.chapter11.SparkMachineLearning

import org.apache.spark.sql.SparkSession
import org.apache.spark.mllib.feature.PCA
import org.apache.spark.mllib.util.MLUtils
import org.apache.spark.mllib.regression.LinearRegressionWithSGD

object PCAExample2 {
  def main(args: Array[String]): Unit = {
    val spark = SparkSession
      .builder
      .master("local[*]")
      .config("spark.sql.warehouse.dir", "E:/Exp/")
      .appName(s"OneVsRestExample")
      .getOrCreate()

    val data = MLUtils.loadLibSVMFile(spark.sparkContext, "data/mnist.bz2")
    val df = spark.read.format("libsvm").load("C:/Exp/mnist.bz2")
    df.show(20)
    
    val featureSize = data.first().features.size
    println("Feature Size: " + featureSize)

    val splits = data.randomSplit(Array(0.75, 0.25), seed = 12345L)
    val (training, test) = (splits(0), splits(1))


    val pca = new PCA(featureSize/2).fit(data.map(_.features))
    val training_pca = training.map(p => p.copy(features = pca.transform(p.features)))
    val test_pca = test.map(p => p.copy(features = pca.transform(p.features)))

    val numIterations = 20
    val stepSize = 0.0001
    val model = LinearRegressionWithSGD.train(training, numIterations, stepSize)
    val model_pca = LinearRegressionWithSGD.train(training_pca, numIterations, stepSize)

    val valuesAndPreds = test.map { point =>
      val score = model.predict(point.features)
      (score, point.label)
    }

    val valuesAndPreds_pca = test_pca.map { point =>
      val score = model_pca.predict(point.features)
      (score, point.label)
    }

    val MSE = valuesAndPreds.map { case (v, p) => math.pow(v - p, 2) }.mean()
    val MSE_pca = valuesAndPreds_pca.map { case (v, p) => math.pow(v - p, 2) }.mean()

    println("Mean Squared Error = " + MSE)
    println("PCA Mean Squared Error = " + MSE_pca)  
    
    println("Model coefficients:"+ model.toString())
    println("Model with PCA coefficients:"+ model_pca.toString())
    

    spark.stop()

  }
}